Filter conveyor band for a continuously operating filter press

ABSTRACT

A filter conveyor band for a continuously operating filter press comprising a plurality of hingedly interconnected links, and means defining a drainage channel at the rear face of each link. The drainage channel includes a portion widening in the direction of the rear end of each such link, with the rear drainage surface of each link opening into its drainage channel. Each drainage channel is equipped at the forward end thereof, as regards the direction of movement of the band, with narrowing guide shoulder or projection means which protrude into the widened portion of the drainage channel of the next forwardly disposed link.

United States Patent Gujer [54] FILTER CONVEYOR BAND FOR A CONTINUOUSLY OPERATING FILTER PRESS [72] Inventor: Hans Guier, Glattalstrasse 149,

Rurnlang, Switzerland [22] Filed: Nov. 19, 1970 [21] Appl. No.: 91,121

[30] Foreign Application Priority Data Nov. 25,1969

[52] US. Cl. ..2l0/324, 100/118, 210/401 [51] Int. Cl ..B0ld 33/04, B30b 9/02 [58] Field of'Search ..2l0/324, 401;200/118, 152

[56] References Cited UNTIED STATES PATENTS 3,581,901 6/1971 Gujer ..210/401-x Switzerland 17530/69 151 3,687,295 [451 Aug. 29,1972

Primary ExaminerFrank A. Spear, Jr. Attomey-Wemer W. Kleeman ABSTRACT A filter conveyor band for a continuously operating filter press comprising a plurality of hingedly interconnected links, and means defining a drainage channel at the rear face of each link. The drainage channel includes a portion widening in the direction of the rear end of each such link, with the rear drainage surface of each link opening into its drainage channel. Each drainage channel is equipped at the forward end thereof, as regards the direction of movement of the band, with narrowing guide shoulder or projection means which protrude into the widened portion of the V drainage channel of the next forwardly disposed link.

3ClainB,4Drawing Figures PATENTEDwczs um 3,687,295

INVENTOR. lid/vs Guam BY weR/veR M dis/mam FHJTER CONVEYOR BAND FOR A CONTHIUOUSLY OPERATING FILTER PRESS BACKGROUND OF THE INVENTION The present invention relates to a new and improved filter conveyor band for a continuously operating filter press of the type incorporating link elements which are hingedly joined together and wherein such link elements or links are equipped with fiow-off or drainage means. The instant invention constitutes an improvement upon the filter conveyor band construction which is the subject of the copending United States application, Ser. No. 838,296, filed July 1, 1969, now US. Pat. No. 3,581,901 and entitled A FILTER CONVEYOR BAND FOR A CONTINUOUSLY OPERATING FILTER PRESS, assigned to the applicant of this application and listing therein both applicant and Karl Koller as inventors.

In the aforementioned copending United States application of applicant, there is disclosed a filter conveyor band for a continuously operau'ng filter press which embodies a number of articulated or hingedly connected links or link elements equipped with drainage devices. According to the development disclosed in that application, the drainage devices embody drainage grooves extending in the conveying direction, which grooves, viewed again in the conveying direction, are closed at the rear end and are open at the front end and towards the rear face of the associated link. Furthermore, according to the invention of that application, the webs or ribs separating the drainage grooves from one another are inclined at their forward end and are directed away from the filter surface, in other words away from the top surface of each such web or rib. Moreover, the inclined surface of each such rib cooperates with an appropriately or correspondingly inclined rear drainage surface or web of the leading link, which drainage surface extends transverse to the conveying apparatus, and specifically, this cooperation is such that the forward ends of the ribs or webs, when the filter conveyor band is in its extended or stretched condition, at least approximately adjoin the rear drainage surface of the next leading link and when the filter conveyor band is curved defines a gap narrowing in a direction away from the top surface of the ribs.

Now, it has been found that the withdrawal of the filtered liquid at the rear face of the filter conveyor bmtds in many situations is not completely satisfactory. It can happen, particularly if there is a large amount of liquid, that the liquid again flows back at the connection or articulation locations of the links with one another and the liquid which once was pressed out of the pressed material again flows back into such material.

SUMIVIARY OF THE INVENTION Accordingly, a primary object of the present invention is to provide a filter conveyor band construction which avoids the aforementioned drawbacks.

Another object of the present invention relates to an improved filter conveyor band which possesses a construction improving upon the operation of the filter conveyor band arrangement of the aforementioned copending United States application, and specifically, to ensure for a faultless withdrawal of the filtered-out liquid.

Another noteworthy object of the present invention relates to an improved filter band construction for a filter press which is not only relatively simple in construction, economical to manufacture, reliable in operation, easy to assemble and disassemble, and affords for good removal of the filtered fluid or liquid materials, but additionally, provides a construction which minimizes the possibility of any withdrawn liquid from returning back to the pressed material.

Now, in order to implement these and still further objects of the present invention, which will become more readily apparent as the description proceeds, the invention contemplates an improved construction of filter conveyor band for a continuously operating filter press which is of the type incorporating a plurality of hingedly interconnected links, each link being equipped with drainage means. The drainage means of each link comprises drainage grooves extending in the direction of travel of the filter band. Viewed in the direction of travel of the filter band each link has its drainage groove closed at its rear end andopen at its forward end and in a direction towards the rear face of the associated link. The ribs which extend longitudinally of the body and separate the grooves from one another each include a forward end which is inclined forwardly of and away from the top surface of the associated rib and which cooperates with a rear ledge member of the next forwardly arranged link, which ledge member closes off the rear of the drainage groove of such next forwardly arranged link, is inclined correspondingly with respect to the front inclined end of the adjacent rib, and further defines a rear drainage surface. The downward inclined end of each rib cooperates with the inclined rear drainage surface of the next leading link in such a manner that when the filter conveyor band is in extended or stretched condition such forward inclined end of the rib approximately adjoins the rear drainage surface of the ledge of the next forward or leading link and when the filter conveyor band is .in a curved condition such forward inclined end of each rib and its adjacent rear drainage surface form a gap which narrows or tapers in a direction away from the filter surface, in other words in a direction away from the top surface of the corresponding ribs. According to an important aspect of the invention, the rear face of the portion of each link possessing the drainage groove is provided with a drainage channel which widens in a direction towards the rear end of the associated link and into which opens the rear ledge of the rear drainage surface, and additionally, each such drainage channel at its forward end possesses narrowing guide projection or shoulder means which extend into the widened portion of the drainage channel of the next forwardly situated link.

The drainage channels arranged at the region of the rear face of the links ensure for a positive guiding of the liquid. The guide projection means which open into the widened portion of the drainage channel of the next forwardly disposed link especially ensure that at the region of the gap between each two links the liquid is guided in such a manner that liquid which has already been pressed out of the pressed material cannot again flow back into such gap. Accordingly, once liquid has been withdrawn away from the filter surfaces it is positively removed.

BRIEF DESCRIPTION OF THE DRAWING FIG. 2 is a longitudinal sectional view of the link ele- I ment of the invention shown in FIG. 1, taken substantially along the lines II-II thereof;

FIG. '3 is a fragmentary view showing details of the cooperative interrelationship between two neighboring link elements during such time as the filter conveyor band is in its stretched or elongated condition; and FIGA is a view similar to FIG. 3, but this time showing the cooperation of two neighboring link elements during such time as the filter conveyor band is in a curved condition or state.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Describing now the drawing, in FIGS. 1 and 2 there is illustrated the details of a preferred construction bf link element or link 20 of a filter conveyor band for a continuously operating filter press. Each such link 20 will be seen to be equipped with drainage grooves l separated from one another by means of the ribs or webs 2 which extend in the lengthwise direction of travel of the filter conveyor band. The ends 3 of the drainage grooves 1, which constitute the rear ends of such drainage grooves when viewed in the direction of travel of the conveyor band, are closed by an as sociated web or ledge 5 which is forwardly inclined in a direction away from the filter surface 4. The forward ends 6 of these drainage grooves 1 are open towards the front and towards the rear face of the associated link 20. The front end 7 of each rib 2 is likewise inclined away from the conveying or filter surface 4, in other words away from the top surface 2a of the corresponding rib 2, and more particularly, is inclined forwardly and substantially corresponding to the inclination of the rear drainage surfaces defined by the ledge members 5.

According to an important aspect of the present invention, drainage channels 8 are provided at the rear face of the portion of each link element equipped with the drainage grooves 1. The discharge or drainage channels 8 are widened in a direction towards the rear end 8a of such channel and at the opposite forward end such channel is equipped with a tapering or narrowing guide shoulder or projection means 8b. The rear drainage surfaces of the rear ledges 5 open into the widened portion 812 of the corresponding drainage channel 8, so that the liquid withdrawn from the filter surface 4 can be conveyed away by the corresponding discharge or drainage channel 8. Now in order to prevent, particularly when there is a large amount of liquid present, that the liquid at the forward end of the link flows back to the filtered surface through the gap 21 between each drainage groove web 2 and the rearward situated ledge 5 of the forward link element and via the drainage groove openings 6, the tapered guide projections 81; of each of the discharge or drainage channel 8 of each link 20, in each instance, protrude into the widened portion 8a of the drainage channel 8 of the next forward situated link element. In this manner it is ensured that there is a faultless withdrawal of the liquid at the rear face of the filter conveyor band. It is possible for the drainage channels 8 to be open towards the rear face 15 of the filter conveyor band, but, however, it is more advantageous if such'drainage channels 8 are each equipped with a cover or closure member 11, simultaneously serving to brace the filter conveyor band upon a support.

Continuing, it will be observed that each link member 20 is provided at its forward and rearward ends with the eyelets 9, 10 which can be arranged in offset relationship with respect to one another and serve to interconnect the individual link elements with one another. These eyelets 9, Ill-simultaneously also perform the function of cams, which can cooperate with a suitable drive or sprocket wheel of the filter Pr The links 20 of the filter conveyor band can preferably be formed of plastic. Polyoxymethylene, known commercially as DELRIN has proven to be particularly useful.

In manner of operation of the filter conveyor band or belt arranged in a vertical filter tower will now be considered and is as follows: two filter conveyor bands collectively form a downwardly tapering or narrowing filter press cavity and are covered with a filter cloth at the filtered surface 4. As is known in'this type of equip ment, the filter conveyor band travels downwardly, thereby exerting compressive forces upon the pressed material. The thus extracted liquid enters into the drainage grooves 1 and flows downwardly unn'l arrives at the ledge or web 5 of the leading or forwardly situated link element, which ledge or web forms a rear drainage surface. Due to the inclination of this ledge or strip 5, the liquid is deflected at the rear side of the link into the associated discharge or drainage channel 8 and withdrawn in a downward direction. Since the ends 7 of the webs 2 are inclined in accordance with the inclination of the ledge or strip members 5 and at least approximately adjoin or neighbor such ledges S, a gap is formed between the ends 7 of the webs 2 and the ledge members 5, the capillary action of which favors a frictionless withdrawal of the liquid. The flow of the emerging liquid at the link elements 20 of the filter conveyor band has been indicated in FIG. 3 by phantom lines. Hence, it should be apparent that at the rear face of the link elements the liquid is conveyed from one discharge or drainage channel 8 to the next discharge or drainage channel of each successive link 20. The guide projections 8b of each of the discharge channels 8 of the individual links are preferably arranged to extend so deeply into the widened portion'8a of the next neighboring cooperating drainage channel of the next forward arranged or leading link element, that such depending guide projection means 8b opens beneath the mouth of the drainage surfaces of the rear ledge members 5. Consequently, the return flow of liquid between the gaps 21 of the link elements and the openings 6 of the drainage grooves 1 is efiectively prevented.

At the lower end of the press cavity, the filter conveyor bands are deflected and thereby release the filter cake. In order to prevent that possible residual drops are again taken-up by the slackened or relaxed filter cake during the deflection of the filter conveyor bands, the link elements are constructed such that during such deflection of the conveyor band they form a slot 21 between the forward ends 7 of the ribs 2 of each rearward or trailing link and the rear surface of the web or ledge 5 of the next leading link, which slot narrows or tapers in a direction away from the filter surface 4 and the top surface of the ribs 2. As a result, a capillary action is produced at the side of the slot facing away from the filter surface, this capillary action or force drawing-off also the last liquid droplets rearwardly away from the filter surface 4. Hence, there is attained a faultless withdrawal of the liquid from the filter sur-' face and the filter cloth. During the course of the increasing deflection of the individual link elements 20 of the filter conveyor band at the lower end of the filter press cavity, the link elements form an opening between the forward ends 7 of the webs 2 and the ledge 5 of the forwardly situated link, which opening renders possible the escape of the liquid from the discharge or drainage channels at the rear side of the links. This opening of the link elements takes place at such a great distance from the press cavity that the escaping liquid can no longer return into the press cavity and into contact with the pressed material.

While there is shown and described present preferred embodiments of the invention, it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied and practiced within the scope of the following claims. AC- CORDINGLY.

What is claimed is:

1. A filter conveyor band for a continuously operating filter press comprising a plurality of hingedly interconnected links, each link comprising a body having drainage grooves extending in the direction of movement of the band, means closing the rear end of each groove, each groove being open at its forward end and in a direction towards the rear face of the associated link, ribs extending longitudinally of the body and separating said grooves, each said ribs including a top surface and a forward end inclined forwardly of and away from the plane of the top surface of said ribs, said means closing the rear end of each groove having a rear drainage surface as regards the direction of movement of said band that is inclined substantially correspondingly to the inclinau'on of the forward end of said ribs whereby said forward ends of said ribs cooperate with said rear drainage surface so as to at least approximately adjoin such rear drainage surface when the band is in a substantially straight condition and to define a gap which narrows in a direction away from the top surface of said ribs when the bandis in curved condition, means defining a drainage channel at the rear face of each link, said drainage channel including a portion widening in the direction of the rear end of each such link, said rear drainage surface of each link opening into said drainage channel thereof, each drainage channel being equipped at the forward end thereof, as regards the direction of movement of the band, with narrowing guide shoulder means which protrude into the widened portion of the drainage if i iiit e i' fiiiti lld ififii in claim 1, wherein each rear drainage surface includes a mouth portion, each drainage channel opening beneath the mouth portion of its associated rear drainage surface.

3.. A filter conveyor band as defined in claim 1, further including cover means at the rear face of each link provided for each associated drainage channel. 

1. A filter conveyor band for a continuously operating filter press comprising a plurality of hingedly interconnected links, each link comprising a body having drainage grooves extending in the direction of movement of the band, means closing the rear end of each groove, each groove being open at its forward end and in a direction towards the rear face of the associated link, ribs extending longitudinally of the body and separating said grooves, each said ribs including a top surface and a forward end inclined forwardly of and away from the plane of the top surface of said ribs, said means closing the rear end of each groove having a rear drainage surface as regards the direction of movement of said band that is inclined substantially correspondingly to the inclination of the forward end of said ribs whereby said forward ends of said ribs cooperate with said rear drainage surface so as to at least approximately adjoin such rear drainage surface when the band is in a substantially straight condition and to define a gap which narrows in a direction away from the top surface of said ribs when the band is in curved condition, means defining a drainage channel at the rear face of each link, said drainage channel including a portion widening in the direction of the rear end of each such link, said rear drainage surface of each link opening into said drainage channel thereof, each drainage channel being equipped at the forward end thereof, as regards the direction of movement of the band, with narrowing guide shoulder means which protrude into the widened portion of the drainage channel of the next forwardly disposed link.
 2. A filter conveyor band as defined in claim 1, wherein each rear drainage surface includes a mouth portion, each drainage channel opening beneath the mouth portion of its associated rear drainage surface.
 3. A filter conveyor band as defined in claim 1, further including cover means at the rear face of each link provided for each associated drainage channel. 